Topic
Urea
About: Urea is a research topic. Over the lifetime, 21394 publications have been published within this topic receiving 382444 citations. The topic is also known as: carbamide & carbonic acid diamide.
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112 citations
TL;DR: In this paper, the effect of sugar, glucose, guanidine hydrochloride, or urea on the dynamic elastic modulus and mechanical loss tangent of agarose gels were examined.
Abstract: The effect of sucrose, glucose, guanidine hydrochloride, or urea on the dynamic elastic modulus E' and mechanical loss tangent and on the differential scanning calorimetry (DSC) curves of agarose gels were examined. E' increased with increasing concentration of sugars up to a certain amount, but the excessive addition of sugars decreased E'. The DSC endothermic peak accompanying the transition from gel to sol shifted to higher temperatures, while the heat absorbed on forming 1 mol of junction zones increased and then decreased with increasing sugar concentration. Guanidine hydrochloride or urea decreased E' and shifted the gel to sol transition temperature to lower temperatures. The mechanism by which these chemical reagents weaken or strengthen the gel-forming ability was discussed
112 citations
TL;DR: Two thiourea and urea based indole conjugated ligands show selective color changes with fluoride along with an absorbance band at 936 nm and 904 nm respectively.
111 citations
TL;DR: The ATP:urea amido-lyase reaction of yeast has been shown to consist of two distinct activities, an avidin-sensitive, thiourea-insensitive urea carboxylase and an avidine-sensitive allophanate hydrolase.
111 citations
Abstract: A new method of direct immobilization of urease on a hydrated silicon nitride surface with the use of glutaraldehyde is presented. The main parameters characterizing the developed urea biosensor based on pH-ion-selective field effect transistor (pH-ISFET) with directly immobilized urease are: (1) maximal analytical signal, 120–140 mV in 10 mM phosphate buffer solution; (2) linear range of ΔUgs=f(log Curea):pCurea(2–3.5) in 10 mM phosphate buffer; (3) response time, 80 s; and (4) lifetime of 35 days with a stable analytical signal. The biosensor was used for urea determination in blood serum and in hemodialysis fluid with satisfactory results.
111 citations